At the NYC premiere of "Green Zone," "Extra's" AJ Calloway told Damon he was looking trim, and he responded, "I'm chasing three little kids around, man!" Damon is a stepfather to wife Luciana Bozán Barroso's daughter Alexia, and they have two daughters together, Isabella and Gia.

The star says he was inspired by the troops overseas to get back in shape. "When these guys go off to fight, they really get in shape and they don't know what it's going to come down to," he explains. "They're very serious about it."

The Oscar winner also admits that working on "Green Zone" gave him a newfound respect for the men and women who serve. He says, "When you see the guys, you stop and just say 'Thank you.' They're pretty great."